This invention relates to an optical device suitable for a display device having discretely-arranged picture elements such as a liquid crystal display, a plasma display, an EL (Electroluminescence) display or the like, and a solid image pick-up device such as a CCD (Charge Coupled Device) having discretely-arranged picture elements for image pick-up.
When an image display operation of a line sequential scanning type is carried out using an NTSC system or the like in a display device having picture elements which are arranged in a discrete form, for example, in a mosaic form, a dot form or the like on a screen thereof, brightness signals which should be originally analog signals are roughly sampled, and a part of positional information on an image on the screen in a horizontal direction is lost. Further, when the picture-element resolution in a vertical direction which is matched to the number of scanning lines cannot be achieved, it has been hitherto adopted that information of scanning lines is intentionally thinned out or an over-writing is performed on the same picture elements. Therefore, in this method, positional resolution of brightness signals or the like (that is, the resolution of a display) has been reduced.
For example, in a liquid crystal viewfinder of a TFT(Thin-Film-Transistor)-TN(Twisted Nematic) type which is driven in the NTSC system, one frame (that is, a picture displayed on the viewfinder) is formed of two fields which comprise even-numbered scanning lines and odd-numbered scanning lines respectively, and a frame frequency is set to 30 Hz (that is, field frequency is set to 60 Hz).
With respect to a present TFT viewfinder, 525 scanning lines whose number is presently used for the NTSC system cannot be actually provided to the present TFT viewfinder, and thus a method has been adopted in which information on an even field and information on an odd field are over-written on the same picture elements. Therefore, an actual vertical resolution is practically lower than a resolution which is expected on the basis of the principle of the NTSC system.
Further, a mosaic frame having a discrete picture-element arrangement becomes remarkable because picture elements are designed in a large size and such a display device has a joint portion at a non-display picture-element portion (a portion located between neighboring picture elements) such as a black matrix or the like, so that a frame texture is deteriorated.
In view of the foregoing, a method of spatially deviating picture images of odd fields and even fields from each other by using a wobbling technique with a picture-element (pixel) deviating unit has been proposed to improve the vertical resolution. This method may be applied to a horizontal direction to improve the horizontal resolution.
However, any wobbling element which has been hitherto proposed has low-speed responsibility response and thus it cannot be driven at a video rate, so that it is not practically usable. Further, these devices have been designed in an insufficient construction condition.